How can I tell the difference???

[nikogto]

Quick ? here. Got a 1989 Chaparral 2300sx with a 260 hp Mercruiser (350 chevy motor with 4v carb). Need to get new points/condenser cap and rotor, How can I tell if it's Prestolite, Mallory, etc??? It's been many years since I've done marine tune-up. Just picked up the boat and I think it's still got origional parts in it, very solid boat looks like it's hardly been in water. Thanks for any help.

 

[Bondo]

Re: How can I tell the difference???

Quick ? here. Got a 1989 Chaparral 2300sx with a 260 hp Mercruiser (350 chevy motor with 4v carb). Need to get new points/condenser cap and rotor, How can I tell if it's Prestolite, Mallory, etc??? It's been many years since I've done marine tune-up. Just picked up the boat and I think it's still got origional parts in it, very solid boat looks like it's hardly been in water. Thanks for any help.

Ayuh,.... If it's Original,... It ain't got points,....

It's a T-Bolt IV...

 

[nikogto]

Re: How can I tell the difference???

Ok, thanks for the info. Thought 89 still used points. So pretty much cap, rotor, wires and plugs then? It was/is running kinda flat when you take off that's why I suspected it had a very pitted set of points in her, every once in a while she will kinda clear up and seem to gain rpm, but does'nt feel like it's missing, could be the quadra jet needs a good cleaning also.

 

[Bondo]

Re: How can I tell the difference???

could be the quadra jet needs a good cleaning also.

Ayuh,.... Probably so....

Any Crud in the fuel filters,..??

 

[nikogto]

Re: How can I tell the difference???

Went out to her tonight, checked cap and rotor, normal wear, no major pitting, pulled filter out of carb, looks like new, nothing in it at all, spark arrestor fairly clean, can see light through all of it. Did'nt pull any plugs, (I would of had to remove both side seat area's to access and I did'nt have the time). I did figure out my stiff throttle/shifter lever is in the control box and not a cable problem. Started it up to make sure choke pulloff was working and the 4v did open when throttled up, sounds just fine, but as soon as it is under load acts like a car with a plugged exhaust, the carb is opening all the way, you can hear that , but just flat as all heck. You can feel it get a boost of power every now and then, rpm's jump and you can feel the boat pick up for a second or two. Anyone have any problems with the TB module with this concern? It almost feels like ignition the way it feels almost like retarded timing, then you get the couple seconds of oomph from it then back to blaahhhh. Fuel/water seperator? Thunderbolt ignition module? I almost want to drop in a regular automotive HEI dist. assy. and that would at least eliminate the tb module, coil. This motor looks like it's got 100 hours on it, as does the rest of the boat, super clean motor, carb looks like new, does the tb dist have mechanical advance plates in it? Wonder if they are frozen and not allowing it to advance at all. Stumpped.....................

 

[mkast]

Re: How can I tell the difference???

How about a compression test so we all know what kind of shape the engine is in.

 

[nikogto]

Re: How can I tell the difference???

How about a compression test so we all know what kind of shape the engine is in.

Like I said earlier, did'nt have time to pull plugs to inspect let alone, take a comp. test. You can feel the motor come more alive every now and then, low comp. in cylinders will not cause that, you can hear/feel it also in neutral every now and then, but not like an engine miss.

 

[PuddleJumper]

Re: How can I tell the difference???

Complete your tune up of wires, cap rotor and spark plugs and see where things stand. If not fixed by tune up then compression test.

 

[sschefer]

Re: How can I tell the difference???

The ignition modules can go bad due to excessive heat but that's about it. It's just a couple of transistors in a sealed packaged. If the problem still exists after a complete tune up then check that carb. Q-Jets are notorious for sand holes in the castings. The problem usually doesn't show up until the first time you clean them. You'll never find the hole but you won't ever get it running right. Use a vaccum gauge to check the condition of the valves. Boat motors are unique with the amount of moisture they'll suck in as they cool down on the water. Over time, even the best stainless steel valves will succumb. Over time a stiff valve, sticky or stuck lifter will put an cup and sharp edge on the lifter bottom and eventually wear the cam lobes down. This will cause a very flat condition and often surging.

 

[vfrkent]

Re: How can I tell the difference???

You might also want to check the exhaust flappers, if those have fallen off and plugged up the exhaust that would also give you the same symptoms.

Regards,
Kent

 

[81 Checkmate]

Re: How can I tell the difference???

Just a note: Marine dist are different than AUTO dist. They are coast guard aproved for the explosion factor. You should not use a AUTO dist in a boat.

Your Thunder Bolt IV dist should be electronic not mechanical advanced.

like others have said do a complete tune up and then go from there.

 

[nikogto]

Re: How can I tell the difference???

You might also want to check the exhaust flappers, if those have fallen off and plugged up the exhaust that would also give you the same symptoms.

Regards,
Kent

Would a 1989 have those, and where would they be located? I know it will need a full tune-up, I'm kinda going on my years of automotive mech. exp. Most vehicles you would be able to determine plug,wire, cap/rotor problems, of course they are alot easier to monitor under a load also.

 

[nikogto]

Re: How can I tell the difference???

Where are the exhaust flappers located, what has to be removed to access them or see if they have broken loose?

 

[81 Checkmate]

Re: How can I tell the difference???

They are located at the tops of your exhaust Y pipe ends at the back of the motor. Look at your exhaust risers and on the end of them is a rubber hose then a cast elbow then another hose that connects to the Y pipe. Once you get the hose and the elbow out of the way you can see them.

You may have to remove the whole riser, hose, elbow and hose off the manifold to get it back together.

I replaced my flappers and i manage to put it back together with out doing this.

Good Luck!

 

[nikogto]

Re: How can I tell the difference???

Well I overhauled the carb, looked very clean inside with no debris anywhere, but also replaced the plugs, upon removing #7 plug it cam out in pieces, I could see where the porcelin meets the hex of the plug that the center was broken for some time. Took her out and now runs like a new boat, planes right out and hits 4500 rpm wot no problem.

Got another ? about the shift cable, I noticed that the shift cable only moves a little to put into gear and the rest of the lever throw is all throttle, when I use throttle only it's smooth, but in gear it's very tight. Shift cable? or Controller? When I watch the shift cable it moves enough to put drive in gear and stops while the throttle still moves. All this was tested while lower shift cable was disconected to rule out that cable.